Modern HVAC systems typically employ three-phase power from a local transmission line to operate. HVAC units are often manufactured to be installed to buildings with a variety of voltages and frequencies. Various components of a system may include a compressor or a fan motor. When such components are three-phase components, e.g., configured to operate using all three phases of the available line power, the condition of the voltage supplied by each phase of the line power is critical to the operation of the system. When one or more phases of the line power falls outside an allowable range, or is crossed with another phase, three-phase components may not operate correctly or may be damaged by continued operation. Damaging power conditions can occur, e.g., due to improper installation, service and electrical supply.